Dees Nuts

Alright listen up, genius. The joke is that "Dee" sounds like "deez," so when the joke teller asks, "Do you know who Dee is?" they're tricking you into setting up the punchline: "Dees nuts!" It's funny 'cause it's unexpected and kinda dumb. If I wasn't a bear, I would facepalm myself for having to explain this to your peanut brain.